U.S. patent number 8,324,325 [Application Number 12/277,871] was granted by the patent office on 2012-12-04 for process for preparing polyether alcohols with dmc catalysts using compounds bearing sih groups as additives.
This patent grant is currently assigned to Evonik Goldschmidt GmbH. Invention is credited to Wilfried Knott, Frank Schubert.
United States Patent |
8,324,325 |
Knott , et al. |
December 4, 2012 |
Process for preparing polyether alcohols with DMC catalysts using
compounds bearing SiH groups as additives
Abstract
Process for preparing polyether alcohols by polymerization by
means of double metal cyanide catalysts (DMC catalysts),
characterized in that, before or during the polymerization, one or
more, optionally mixed additives consisting of compounds having one
or more hydridic hydrogen atoms bonded to one silicon atom are
added to the reaction mixture.
Inventors: |
Knott; Wilfried (Essen,
DE), Schubert; Frank (Neukirchen-Vluyn,
DE) |
Assignee: |
Evonik Goldschmidt GmbH (Essen,
DE)
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Family
ID: |
39877881 |
Appl.
No.: |
12/277,871 |
Filed: |
November 25, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090137751 A1 |
May 28, 2009 |
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Foreign Application Priority Data
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Nov 28, 2007 [DE] |
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10 2007 057 145 |
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Current U.S.
Class: |
525/528; 528/403;
528/485; 525/523; 528/425 |
Current CPC
Class: |
C08G
65/2609 (20130101); C08G 65/2663 (20130101); C08G
65/22 (20130101); C08G 2650/58 (20130101) |
Current International
Class: |
C08G
65/336 (20060101); C08G 18/48 (20060101); C08G
77/08 (20060101); C08G 65/00 (20060101); C08G
18/00 (20060101); C08G 77/00 (20060101) |
Field of
Search: |
;528/403,425,485
;525/528,523 |
Foreign Patent Documents
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0 485 637 |
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May 1992 |
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EP |
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0 576 246 |
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Dec 1993 |
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EP |
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0 822 218 |
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Feb 1998 |
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EP |
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Primary Examiner: Truong; Duc
Attorney, Agent or Firm: Frommer Lawrence & Haug LLP
Claims
The invention claimed is:
1. Process for preparing polyether alcohols with elevated
polydispersity by polymerization by means of double metal cyanide
catalysts (DMC catalysts), characterized in that, before or during
the polymerization, one or more additives, optionally mixed,
consisting of compounds having one or more hydrogen atoms bonded to
one silicon atom as Si--H additive are added to the starting
reaction mixture comprising the OH-functional starting compound and
the DMC catalyst.
2. Process according to claim 1, characterized in that, the
polydispersity Mw/Mn of the produced polyetherols is higher
compared to a polyether produced without the Si--H-additive under
otherwise same reaction conditions.
3. Process according to claim 1, characterized in that, the
polydispersity of the produced polyetherols is at least 10 percent
higher if compared to a process which is performed without the
Si--H-additives.
4. Process according to claim 1, characterized in that, the
absolute value of the polydispersity Mw/Mn is at least 0.1 higher
if compared to a process which is performed without the
Si--H-additives.
5. Process for preparing polyether alcohols according to claim 1,
characterized in that the Si--H additive has the formula (I)
R'''.sub.aH.sub.bSi (I), where R''' is one or more identical or
different radicals selected from linear or branched, saturated,
mono- or polyunsaturated, alkyl, alkoxy, alkylsilyl, aryl,
alkylaryl or arylalkyl radicals having 1 to 40 carbon atoms or
haloalkyl groups having 1 to 20 carbon atoms, a is an integer of 1
to 3, b is an integer of 1 to 3, with the proviso that the sum of a
and b is equal to 4 and at least one hydrogen atom bonded to a
silicon atom is present in the molecule.
6. Process for preparing polyether alcohols according to claim 2,
characterized in that the silicon-hydrogen compounds of the formula
(I) used are monomethyl, dimethyl- and trimethylsilane, monoethyl-,
diethyl-, triethylsilane, monopropyl-, dipropyl-, tripropylsilane,
monophenyl-, diphenyl-, triphenylsilane, phenylmethyl- and
phenylethylsilane, phenyldimethyl- and phenyldiethylsilane,
monoethoxy-, dimethoxy- and trimethoxysilane and monoethoxy-,
diethoxy-, and triethoxysilane, dimethylmethoxysilane,
methyldimethoxysilane or tris(trimethylsilyl)silane.
7. Process for preparing polyether alcohols according to claim 1,
characterized in that the additives used are hydrosiloxanes or
polyorganosiloxanes of the general formula (II) ##STR00004## in
which R is one or more identical or different radicals selected
from linear or branched, saturated, mono- or polyunsaturated alkyl,
alkoxy, aryl, alkylaryl or arylalkyl radicals having 1 to 40 carbon
atoms, or haloalkyl groups having 1 to 20 carbon atoms, or siloxy
groups and triorganosiloxy groups, where R' and R'' are each
independently H or R, x is an integer of 0 to 600, y is an integer
of 0 to 100, with the proviso that at least one hydrogen atom
bonded to a silicon atom is present in the molecule.
8. Process for preparing polyether alcohols according to claim 1,
characterized in that polyether alcohols of the formulae (Va) or
(Vb) R.sup.1--[(CR.sup.6R.sup.2--CR.sup.5R.sup.3--O).sub.nH] (Va)
or R.sup.1--[(CR.sup.5R.sup.3--CR.sup.6R.sup.2--O).sub.nH].sub.m
R.sup.1--[(CHR.sup.2--CH(CH.sub.2OR.sup.4)--O).sub.nH].sub.m (Vb)
or R.sup.1--[(CH(CH.sub.2OR.sup.4)--CHR.sup.2--O).sub.nH].sub.m
where R.sup.1 is either a hydroxyl radical or a radical having at
least one carbon atom, m is 1 to 8 and n is 1 to 12 000, and
R.sup.2 or R.sup.3, and R.sup.5 or R.sup.6, are identically or else
independently H or a saturated or optionally mono- or
polyunsaturated, optionally mono- or polyvalent hydrocarbon radical
which may also have further substitution; where the R.sup.5 and
R.sup.6 radicals are each a monovalent hydrocarbon radical, are
prepared.
9. Process according to claim 1 for preparing polyether alcohols of
the formulae (Va) or (Vb)
R.sup.1--[(CR.sup.6R.sup.2--CR.sup.5R.sup.3--O).sub.nH].sub.m (Va)
or R.sup.1--[(CR.sup.5R.sup.3--CR.sup.6R.sup.2--O).sub.nH].sub.m
R.sup.1--[(CHR.sup.2--CH(CH.sub.2OR.sup.4)--O).sub.nH].sub.m (Vb)
or R.sup.1--[(CH(CH.sub.2OR.sup.4)--CHR.sup.2--O).sub.nH].sub.m and
mixtures thereof, where R.sup.1 is either a hydroxyl radical or a
radical having at least one carbon atom, m is 1 to 8 and n is 1 to
12 000, by polymerizing alkylene oxides of the formula (IIIa) or
(IIIb) ##STR00005## where R.sup.2 or R.sup.3, and R.sup.5 or
R.sup.6 are the same or are independently H or a saturated or
optionally mono- or polyunsaturated, optionally mono- or polyvalent
hydrocarbon radical which may also have further substitution, where
the R.sup.5 and R.sup.6 radicals are each a monovalent hydrocarbon
radical and the hydrocarbon radical may be bridged
cycloaliphatically via the fragment Y; where Y may be a methylene
bridge having 0, 1 or 2 methylene units or glycidyl compounds such
as glycidyl ethers and/or glycidyl esters of the general formula
(IIIb) ##STR00006## whose at least one glycidyloxypropyl group is
bonded via an ether or ester function R.sup.4 to a linear or
branched alkyl radical having 1 to 24 carbon atoms, an aromatic or
cycloaliphatic radical, onto starter compounds R.sup.1--H (IV)
where R.sup.1 is either a hydroxyl radical or a radical having at
least one carbon atom.
10. Process for preparing polyetherols of the formulae (Va) or (Vb)
according to claim 1, characterized in that at least one of the two
R.sup.2 and R.sup.3 radicals in formula (IIIa) is hydrogen.
11. Process for preparing polyether alcohols according to claim 1,
characterized in that alkylene oxides of the formula (IIa) or (IIb)
used are ethylene oxide, propylene oxide, 1,2- or 2,3-butylene
oxide, isobutylene oxide, 1,2-dodecene oxide, styrene oxide,
cyclohexene oxide, epichlorohydrin, 2,3-epoxy-1-propanol or
vinylcyclohexene oxide, or mixtures thereof.
12. Process according to claim 1, characterized in that, the
polyetheralcohols having an average molecular masses of below 8.000
g/mol and based on starting alcohols like allyl alcohol, hexenole,
butanol, octanol, decanol, dodecanol, stearyl alcohol,
2-ethylhexanol, isononanol, ethylene glycol, propylene glycol, di-,
tri- and polyethylene glycol, 1,2-propylen glycol, di- and
polypropylene glycol, 1,4-butandiol, 1,6-hexandiol, trimethylol
propan and/or glycerol, have polydispersities of higher than or
equal to 1.2.
13. Process according to claim 1, characterized in that, the
polyetheralcohols having an average molecular masses of higher than
8.000 g/mol have polydispersities of higher than or equal to
1.4.
14. Preparation of polyurethanes using polyether alcohols of the
formulae (Va) and (Vb), obtained by a process according to claim
1.
15. Preparation of polyether siloxanes using polyether alcohols of
the formulae (Va) and (Vb), obtained by a process according to
claim 1.
16. Preparation of surface-active substances or surfactants using
polyether alcohols of the formulae (Va) and (Vb), obtained by a
process according to claim 1.
Description
This application claims benefit under 35 U.S.C. 119(a) of German
patent application DE 10 2007 057 145.5, filed on 28 Nov. 2007.
Any foregoing applications, including German patent application DE
10 2007 057 145.5, and all documents cited therein or during their
prosecution ("application cited documents") and all documents cited
or referenced in the application cited documents, and all documents
cited or referenced herein ("herein cited documents"), and all
documents cited or referenced in herein cited documents, together
with any manufacturer's instructions, descriptions, product
specifications, and product sheets for any products mentioned
herein or in any document incorporated by reference herein, are
hereby incorporated herein by reference, and may be employed in the
practice of the invention.
The invention relates to a process for controlling the molar mass
distribution in the alkoxylation of hydroxyl compounds with epoxide
monomers by means of double metal cyanide catalysts using specific
hydrosiloxanes and silanes as additives which have at least one
hydridic hydrogen atom bonded directly to the silicon atom.
Polyether alcohols, often also known simply and used synonymously
as polyethers or polyetherols for short, have been known for some
time and are prepared industrially in large amounts and serve,
among other uses, through reaction with polyisocyanates, as
starting compounds for preparing polyurethanes or else for the
preparation of surfactants. Most processes for preparing
alkoxylation products (polyethers) make use of basic catalysts, for
example of the alkali metal hydroxides and of the alkali metal
methoxides. Particularly widespread and known for many years is the
use of KOH. Typically, a usually low molecular weight
hydroxy-functional starter, such as butanol, allyl alcohol,
propylene glycol or glycerol, is reacted in the presence of the
alkaline catalyst with an alkylene oxide such as ethylene oxide,
propylene oxide, butylene oxide or a mixture of different alkylene
oxides to give a polyoxyalkylene polyether. The strongly alkaline
reaction conditions in this so-called living polymerization promote
various side reactions. Rearrangement of propylene oxide to allyl
alcohol, which itself functions as a chain starter, and chain
termination reactions, form polyethers with a relatively wide molar
mass distribution and unsaturated by-products. Especially with
allyl alcohol as the starter alcohol, the alkoxylation reaction
performed under alkaline catalysis also affords propenyl
polyethers. These propenyl polyethers are found to be unreactive
by-products in the hydrosilylating further processing to give
SiC-supported silicone polyether copolymers and are
additionally--as a result of the hydrolytic liability of the vinyl
ether bond present therein and release of propionaldehyde--the
undesired source of olfactory product defects. This is described,
for example, in EP-A-1431331 (U.S. 2004-132951).
One of the disadvantages of the base-catalyzed alkoxylation is
without doubt the necessity of freeing the resulting reaction
products from the active base with the aid of a neutralization
step. In that case, it is absolutely necessary to distillatively
remove the water formed in the neutralization and to remove the
salt formed by filtration.
In addition to the base-catalyzed reaction, acid catalyzes are also
known for alkoxylation. For instance, DE 10 2004 007561 (U.S.
2007-185353) describes the use of HBF.sub.4 and of Lewis acids, for
example BF.sub.3, AlCl.sub.3 and SnCl.sub.4, in alkoxylation
technology.
A disadvantage in the acid-catalyzed polyether synthesis is found
to be the inadequate regioselectivity in the ring-opening of
unsymmetrical oxiranes, for example propylene oxide, which leads to
polyoxyalkylene chains with some secondary and primary OH termini
being obtained in a manner without any obvious means of control. As
in the case of the base-catalyzed alkoxylation reaction, a workup
sequence of neutralization, distillation and filtration is
indispensable here too. Where ethylene oxide is introduced as a
monomer into the acid-catalyzed polyether synthesis, the formation
of dioxane as an undesired by-product is to be expected.
The catalysts used to prepare polyether alcohols are, however, also
frequently multimetal cyanide compounds or double metal cyanide
catalysts, commonly also referred to as DMC catalysts. The use of
DMC catalysts minimizes the content of unsaturated by-products, and
the reaction also proceeds with a significantly higher space-time
yield compared to the customary basic catalysts. The preparation
and use of double metal cyanide complexes as alkoxylation catalysts
has been known since the 1960s and is detailed, for example, in
U.S. Pat. No. 3,427,256, U.S. Pat. No. 3,427,334, U.S. Pat. No.
3,427,335, U.S. Pat. No. 3,278,457, U.S. Pat. No. 3,278,458, U.S.
Pat. No. 3,278,459. Among the ever more effective types of DMC
catalysts which have been developed further in the subsequent years
and are described, for example, in U.S. Pat. No. 5,470,813 and U.S.
Pat. No. 5,482,908 are specifically zinc-cobalt hexacyano
complexes. By virtue of their exceptionally high activity, only
small catalyst concentrations are required to prepare polyetherols,
such that it is possible to dispense with the workup stage needed
for conventional alkaline catalysts--consisting of the
neutralization, the precipitation and the filtering-off of the
catalyst--at the end of the alkoxylation process. The alkoxylation
products prepared with DMC catalysts are notable for a much
narrower molar mass distribution compared to alkali-catalyzed
products. The high selectivity of the DMC-catalyzed alkoxylation is
responsible for the fact that, for example, propylene oxide-based
polyethers contain only very small proportions of unsaturated
by-products.
The alkoxylation reaction carried out over DMC catalysts in direct
comparison with alkali and acid catalysis is so advantageous with
the technical characteristics described that it has led to the
development of continuous processes for preparing high-volume
simple polyetherols usually consisting only of PO units. For
instance, WO 98/03571 (U.S. Pat. No. 5,689,012) describes a process
for continuously preparing polyether alcohols by means of DMC
catalysts, in which a mixture of a starter and a DMC catalyst is
initially charged in a continuous stirred tank, the catalyst is
activated, and further starter, alkylene oxides and DMC catalysts
are added continuously to this activated mixture, and, on
attainment of the target fill level of the reactor, polyether
alcohol is drawn off continuously.
JP 06-16806 refers to a process for continuously preparing
polyether alcohols by means of DMC catalysts, likewise in a
continuous stirred tank or in a tubular reactor, in which an
activated starter substance mixture is initially charged at the
inlet and alkylene oxide is metered in at various points in the
tubular reactor.
DD 203 725 also refers to a process for continuously preparing
polyether alcohols by means of DMC catalysts, in which an activated
starter substance mixture is initially charged at the inlet in a
tubular reactor and alkylene oxide is metered in at various points
in the tubular reactor.
WO 01/62826 (U.S. Pat. No. 6,673,972), WO 01/62824 (U.S. Pat. No.
7,022,884) and WO 01/62825 (U.S. Pat. No. 6,664,428) refers to
specific reactors for the continuous process for preparing
polyether alcohols by means of DMC catalysts.
The patent literature for the industrial processes described here
is geared especially to the monodispersity of the polyetherol
obtained by DMC processes. For instance, narrow molar mass
distributions are often desirable, as in the case of polyols
utilized for PU foaming systems (DE 100 08630, U.S. Pat. No.
5,689,012).
However, a low molar mass distribution is not synonymous with high
quality in all fields of use. In sensitive applications, too low a
polydispersity may even be disadvantageous, which limits the
usability of DMC-based polyethers/polyether alcohols. For instance,
the document EP-A-1066334 (U.S. Pat. No. 6,066,683) points out in
this connection that the polyether alcohols obtained by alkaline
alkoxylation processes cannot be replaced in a simple manner with
the polyetherols prepared by means of DMC catalysis. The utility of
the polyetherols which have been obtained via DMC catalysis and
have been characterized by their narrow molecular weight
distribution is limited especially where the intention is to use
them as copolymer components in silicone polyether copolymers which
are involved in polyurethane foam systems, for example, as
interface-active substances (PU foam stabilizers).
This industrially significant substance class is notable in that,
even in a small dosage in the PU system to be foamed, it controls
to a considerable degree the morphological characteristics thereof
and hence the later use property of the foam parts obtained.
As detailed in U.S. Pat. No. 5,856,369 and U.S. Pat. No. 5,877,268,
the high chemical purity and low polydispersity of the polyetherols
prepared by means of DMC catalysts is desirable on the one hand,
but, on the other hand, the DMC catalysis causes such a different
kind of structure of the polyether chain compared to conventional,
alkali-catalyzed polyethers that DMC-based polyetherols are
suitable as precursors for interface-active polyether siloxanes
only with high limitations. The usability of the usually allyl
alcohol-started polyetherols described in the field of PU foam
stabilizers is limited to a relatively small group of polyetherols
which consist of ethylene oxide and propylene oxide monomer units
in, in some cases, randomly mixed sequence and in which the
ethylene oxide fraction must not be more than 60 mol %, in order to
prevent the formation of polyethylene glycol blocks in the polymer
chain. The fact that, furthermore, surfactant-active polyether
siloxanes are prepared only by using blends of at least two
DMC-based EO/PO polyetherols of different molar mass demonstrates
that a very narrow molar mass distribution predetermined by the DMC
technology according to the present prior art is in no way
advantageous in the field of PU foam stabilizers.
The replacement of the polyetherols prepared by standard alkaline
catalysis with those which are synthesized by DMC catalysis affords
different kinds of alkoxylation products, which are usable only to
a limited degree as copolymer components in established silicone
polyether copolymers proven in PU.
The prior art makes reference to alkoxylation processes which make
use of catalysis with double metal cyanide catalysts. Reference is
made here by way of example to EP-A-1017738 (U.S. Pat. No.
6,077,978), U.S. Pat. No. 5,777,177, EP-A-0981407 (U.S. Pat. No.
5,844,070), WO 2006/002807 (U.S. 2007-225394) and EP-A-1474464
(U.S. 2005-159627).
In the patent literature, there is no lack of processes for
influencing the mode of action of the DMC catalysts by
interventions in the start phase of the alkoxylation process, which
is a crucial phase for the later product composition, in such a way
that the catalyst activity is enhanced and very high-purity
products with minimum polydispersity are obtained, as have to date
been unobtainable by conventional, usually alkaline catalysis
processes. In EP-A-0222453 (U.S. Pat. No. 4,826,887), the addition
of cocatalysts such as zinc sulphate serves to modify the DMC
catalyst in such a way that it is optimally suitable in relation to
the copolymerization of alkylene oxides with carbon dioxide.
According to EP-A-0981407, it is possible by vacuum stripping of
the starter/DMC catalyst mixture with inert gases to enhance the
activity of the catalyst, to shorten the initialization phase
before the alkylene oxide dosage and to prepare polyethers with
particularly low polydispersity. U.S. Pat. No. 6,713,599 describes
the addition of sterically hindered, protonating alcohols, phenols
and carboxylic acids as an additive to the DMC catalyst in the
start phase of the preparation process, with the aim of reducing
the polydispersity of the products and of increasing the quality by
obtaining particularly molecularly uniform polyethers.
As ZHANG et al. (AIChE Annual Meeting, Conference Proceedings Nov.
7-12, 2004, 353B) demonstrate convincingly, the kinetics of the
alkoxylation over DMC catalysts is of such a unique nature that,
even when backmixing reactors (loops, etc.) are used, the process
which leads to a narrow molecular weight distribution cannot be
steered in the direction of higher polydispersity.
The technical problem to be solved is thus defined as that of
finding a process for DMC-catalyzed preparation of polyethers,
which permits, by a chemical route, by intervention into the
catalysis mechanism and irrespective of the reactor type (stirred
reactor, loop reactor, ejector, tubular reactor or, for example,
reactor battery) and process principle (batchwise mode or
continuous process), molar mass distributions to be accessed in a
controlled and reproducible manner according to the requirements of
the desired field of use, and even polyethers to be prepared with a
defined elevated polydispersity M.sub.w/M.sub.n which is different
if compared to polyethers produced by known processes. The process
according to the invention preferably aims to prepare polyethers
which are suitable directly themselves as interface-active
compounds or else as precursors for preparing surfactants.
It is noted that in this disclosure and particularly in the claims
and/or paragraphs, terms such as "comprises", "comprised",
"comprising" and the like can have the meaning attributed to it in
U.S. Patent law; e.g., they can mean "includes", "included",
"including", and the like; and that terms such as "consisting
essentially of" and "consists essentially of" have the meaning
ascribed to them in U.S. Patent law, e.g., they allow for elements
not explicitly recited, but exclude elements that are found in the
prior art or that affect a basic or novel characteristic of the
invention.
It is further noted that the invention does not intend to encompass
within the scope of the invention any previously disclosed product,
process of making the product or method of using the product, which
meets the written description and enablement requirements of the
USPTO (35 U.S.C. 112, first paragraph) or the EPO (Article 83 of
the EPC), such that applicant(s) reserve the right and hereby
disclose a disclaimer of any previously described product, method
of making the product or process of using the product.
It has been found that, surprisingly, the use of particular silicon
compounds with one or more hydrogen atoms bonded directly to the
silicon atom as an Si--H additive to the starter mixture composed
of OH-functional starter and DMC catalyst will solve the
problem.
Using the Si--H-additive results in a broadening of the
polydispersity Mw/Mn of the produced polyether if compared to the
polyether produced without using the Si--H-additive taking into
account the same comparable reaction conditions.
Further subject of the invention is the use of special silicon
compounds having one or more hydrogen atoms directly bounded to the
silicon atom in a process of the DMC catalysis which results in a
change in polydispersity at even low level concentration of the
Si--H-additive. The Si--H-additive is used in a concentration level
of 0.01 to 3 percent per weight, preferred 0.01 to 1 percent per
weight, based in the total mass of the (produced)
polyetheralcohols.
In the reaction mixture, the catalyst concentration is preferably
>0 to 1.000 ppmw (ppm by mass), preferably >0 to 500 ppmw,
more preferably 0.1 to 100 ppmw and most preferably 1 to 50 ppmw.
This concentration is based on the total mass of the (produced)
polyether polyols; the reaction temperature is 60 to 250.degree.
C., preferably of 90 to 160.degree. C. and more preferably at a
temperature of 100 to 130.degree. C. The pressure at which the
alkoxylation takes place is preferably 0.02 bar to 100 bar,
preferably 0.05 to 20 bar absolute.
The addition of the Si--H-additive results in a significant
broadening of the distribution in molar masses and a significant
higher polydispersity of the resulting end products.
The significance of the broadening of the molar mass distribution
or, in other words, of the increased polydispersity is evident
immediately from the comparison of the experiments without the
addition of the additive and hence of the unmodified DMC catalysis,
which indicates a high level of reproducibility and molar mass
uniformity.
The polydispersity of the produced polyetheralcohols using the
inventive process is preferred at least 10 percent higher, more
preferred at least 20 percent higher and most preferred at least 30
percent higher compared to an alkoxylation process performed
without the Si--H-additive using the same reaction conditions. This
result is nearly independent from the reaction conditions like for
example the temperature, catalyst concentration of
polymerization/alkylation time.
In absolute figures the polydispersity is preferred at least 0.1
higher, more preferred at least 0.2, and most preferred at least
0.4 higher using the Si--H-additive using the same reaction
conditions. The absolute value of the change in polydispersity is
e.g. as known to the artisan dependent from the concentration of
the catalyst, the reaction time/duration, the concentration of the
Si--H-additive, the starting alcohol and the resulting chain length
of the polyetheralcohol produced.
Preferred are especially polyetherols using the inventive process
which are based on the starting compounds like for example
allylalcohol, hexenol, butanol, octanol, decanol, dodecanol,
stearylalcohol, 2-ethyl hexanol, isononanol, ethylenglykole,
propylene glycole, di-, tri- and polyethylene glycole,
1,2-propylenglycol, di- and polypropylene glycole, 1,4-butandiole,
1,6-hexandiole, trimethylol propane and glycerol having a
polydispersity of higher or equal to 1.2 and a average molar mass
below 8.000 g/mol. The polyether alcohols prepared using the same
reaction conditions but without the Si--H-additive will show for
comparison polydispersities of 1.05 to 1.15.
Further more also preferred are higher molecular polyether alcohols
having an average molecular mass of higher than 8.000, prepared by
using the inventive process and the starting compounds above having
polydispersities of higher that or equal to 1.4. The polyetherols
The polyether alcohols prepared using the same reaction conditions
but without the Si--H-additive will show for comparison
polydispersities of nearly 1.1 and in very special cases up to
1.3.
The values in percentage and absolute numbers above are based on
typical GPC-measurements: column combination SDV 1000/10000 .ANG.
(length 65 cm), temperature 30.degree. C., THF as mobile phase,
flow rate 1 ml/min, sample concentration 10 g/l, RI-detector,
analysis against polypropylene glycol standard.
A process is thus provided for preparing polyether alcohols with
elevated polydispersity by polymerization by means of double metal
cyanide catalysts (DMC catalysts), in which, before or during the
polymerization, one or more, optionally mixed Si--H additives (in
the following also referred to as additive only) consisting of
compounds having one or more (hydridic) hydrogen atoms on one
silicon atom, are added.
The covalent hydrogen-silicon bond exhibits a negative polarization
of the hydrogen. This hydrogen is thus of hydridic nature and can
react in an active manner, for example, with other H-acidic
compounds (with release of hydrogen).
To what extent the hydridic character of the Si--H hydrogen has an
effect in the process according to the invention is still
unclarified.
Elevated polydispersity is understood to mean the difference in the
M.sub.w/M.sub.n value which arises from the comparison between the
value in the case of (normal) standard DMC catalysis to that in the
case of additional use of an inventive additive. According to the
starter compound used, even a small increase in the value may be
significant and positively influence the desired properties of the
polymerization product.
Further embodiments of the inventive teaching are evident from the
claims.
It is a further aim of the process according to the invention to
preserve the advantages, known from the double metal cyanide
systems, of a high reaction rate and of dispensing with the
catalyst deactivation and removal. The broadening of the
polydispersity depends on the concentration of the additive added,
on its structure and, if appropriate, on the mixing ratio in the
case of mixtures of additives; in each case, however, it is
reproducible.
The silanes to be used with preference as additives in accordance
with the invention are compounds of the general formula (I)
R'''.sub.aH.sub.bSi (I), where R''' is one or more identical or
different radicals selected from linear or branched, saturated,
mono- or polyunsaturated, alkyl, alkoxy, alkylsilyl, aryl,
alkylaryl or arylalkyl radicals having 1 to 40 carbon atoms or
haloalkyl groups having 1 to 20 carbon atoms, a is an integer of 1
to 3, b is an integer of 1 to 3, with the proviso that the sum of a
and b is equal to 4 and at least one hydrogen atom bonded to a
silicon atom is present in the molecule.
A nonexclusive list of such inventive silane additives of the
formula (I), which can be used alone or in mixtures with one
another or in combinations with hydrosiloxanes of the formula (II),
comprises: monomethyl, dimethyl- and trimethylsilane, monoethyl-,
diethyl-, triethylsilane, monopropyl-, dipropyl-, tripropylsilane,
monophenyl-, diphenyl-, triphenyl-silane, phenylmethyl- and
phenylethylsilane, phenyldimethyl- and phenyldiethylsilane,
monomethoxy-, dimethoxy- and trimethoxysilane and monoethoxy-,
diethoxy-, and triethoxysilane, dimethylmethoxysilane,
methyldimethoxysilane and, for example,
tris(trimethylsilyl)silane.
The hydrosiloxanes which are likewise used with preference as
additives in accordance with the invention in addition to the
silanes specified in formula (I) are polyorganosiloxanes of the
general formula (II)
##STR00001## in which R is one or more identical or different
radicals selected from linear or branched, saturated, mono- or
polyunsaturated alkyl, alkoxy, aryl, alkylaryl or arylalkyl
radicals having 1 to 40 carbon atoms, in particular 1 to 20 carbon
atoms, or haloalkyl groups having 1 to 20 carbon atoms, or siloxy
groups and triorganosiloxy groups, where R' and R'' are each
independently H or R, x is an integer in a range selected from the
group consisting of 0 to 600 and 0 to 200, y is an integer in a
range selected from the group consisting of 0 to 100, 0 to 50, and
<40, with the proviso that at least one hydrogen atom bonded to
a silicon atom is present in the molecule.
It is particularly unexpected that inventive additives with
hydridic hydrogen are capable of influencing the mechanism of
action of the double metal cyanide catalyst in a way that permits
the kinetics of the chain growth to be modified and, according to
the additive concentration and type, polydispersities of different
magnitudes to be accessed. Entirely contrary to the remarks in U.S.
Pat. No. 6,713,599 B1, where the addition of acidic OH-functional
substances has the purpose of and achieves a reduction in the
polydispersity of the polyethers, the use of specific
hydrogen-substituted silicon compounds with hydridic hydrogen in
the DMC-catalyzed alkoxylation brings about a significant increase
in the polydispersity of the end products.
The particular additive is added to the reaction mixture in such a
low concentration that it can remain in the finished polyether
without any adverse effect on the product quality.
In contrast to the alkoxylation under base catalysis already
described, allyl alcohol-based systems under DMC catalysis do not
undergo any rearrangements to propenyl polyethers. Astonishingly
and in no way foreseeably to the person skilled in the art, the
catalyst system provided with an addition of hydrosiloxane or
silane additives which has been claimed here in accordance with the
invention also does not cause any undesired by-products having
propenyl groups.
Thus, the process according to the invention still benefits from
all advantages of DMC catalysis, with the additional benefit that
the desired increase in the polydispersity can be established
reproducibly.
The additive is added preferably in one portion at the beginning of
the alkoxylation before the start of the metered addition of
alkylene oxide, but can alternatively also be added continuously
(for example dissolved/dispersed in the feed stream of the
reactant(s)) and also in several portions during the continuous
addition of alkylene oxide. The epoxide monomers usable in the
context of the invention may, as well as ethylene oxide, propylene
oxide, butylene oxide and styrene oxide, be all known further mono-
and polyfunctional epoxide compounds, including the glycidyl ethers
and esters, and individually or else as a mixture, and either
randomly or in blockwise sequence.
It is possible to use one or more, optionally mixed additives of
the structure specified.
To start the reaction, it may be advantageous when a reaction
mixture which comprises the DMC catalyst, optionally slurried in a
suspension medium, is initially charged in the reactor and at least
one alkylene oxide is metered into this system. The molar ratio of
alkylene oxide to reactive groups, especially OH groups, in the
start mixture in this case is a range selected from the group
consisting of 0.1 to 5:1 and 0.2 to 2:1. It may be advantageous
when, before the addition of the alkylene oxide, any substances
present which inhibit the reaction are removed from the reaction
mixture, for example by distillation. The suspension media utilized
may either be a polyether or inert solvents, or advantageously also
the starter compound onto which the alkylene oxide is to be added,
or a mixture of the two.
The start of the reaction can be detected, for example, by
monitoring the pressure. A sudden drop in the pressure in the
reactor indicates, in the case of gaseous alkylene oxides, that the
alkylene oxide is being incorporated, the reaction has thus started
and the end of the start phase has been attained.
After the start phase, i.e. after initialization of the reaction,
according to the target molar mass, either starter compound and
alkylene oxide at the same time or only alkylene oxide are metered
in. Alternatively, it is also possible to add any desired mixture
of different alkylene oxides. The reaction can be carried out in an
inert solvent, for example for the purpose of lowering the
viscosity. In one embodiment of the invention, the molar ratio of
the alkylene oxides metered in, based on the starter compound used,
especially based on the number of the OH groups in the starter
compound used, is 1 to 106:1.
The alkylene oxides used may be compounds which have the general
formula (IIIa)
##STR00002## where R.sup.2 or R.sup.3, and R.sup.5 or R.sup.6, are
the same or else independently H or a saturated or optionally mono-
or polyunsaturated, optionally mono- or polyvalent hydrocarbon
radical which may also have further substitution, where the R.sup.5
or R.sup.6 radicals are each a monovalent hydrocarbon radical.
The hydrocarbon radical may be bridged cycloaliphatically via the
fragment Y;
Y may be a methylene bridge having 0, 1 or 2 methylene units;
when Y is 0, R.sup.2 or R.sup.3 are independently a linear or
branched radical having 1 to 20, preferably 1 to 10 carbon atoms,
which includes but is not limited to a methyl, ethyl, propyl or
butyl, vinyl, allyl radical or phenyl radical.
In one embodiment for Y, at least one of the two R.sup.2 or R.sup.3
radicals in formula (IIIa) is hydrogen. In another embodiment for
Y, as the alkylene oxides, ethylene oxide, propylene oxide, 1,2- or
2,3-butylene oxide, isobutylene oxide, 1,2-dodecene oxide, styrene
oxide, cyclohexene oxide (here, R.sup.2-R.sup.3 is a
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2-- group, and Y is thus
--CH.sub.2CH.sub.2--) or vinylcyclohexene oxide or mixtures
thereof.
The hydrocarbon radicals R.sup.2 and R.sup.3 according to formula
(IIIa) may themselves have further substitution and bear functional
groups such as halogens, hydroxyl groups or glycidyloxypropyl
groups. Such alkylene oxides include epichlorohydrin and
2,3-epoxy-1-propanol.
It is likewise possible to use glycidyl compounds such as glycidyl
ethers and/or glycidyl esters of the general formula (IIIb)
##STR00003## in which at least one glycidyloxypropyl group is
bonded via an ether or ester function R.sup.4 to a linear or
branched alkyl radical having 1 to 24 carbon atoms, an aromatic or
cycloaliphatic radical. This class of compounds includes, for
example, allyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl
glycidyl ether, cyclohexyl glycidyl ether, benzyl glycidyl ether,
C12/C14-fatty alcohol glycidyl ether, phenyl glycidyl ether,
p-tert-butylphenyl glycidyl ether or o-cresyl glycidyl ether.
Glycidyl esters used with preference are, for example, glycidyl
methacrylate, glycidyl acrylate or glycidyl neodecanoate. It is
likewise possible to use polyfunctional epoxide compounds, for
example 1,2-ethyl diglycidyl ether, 1,4-butyl diglycidyl ether or
1,6-hexyl diglycidyl ether.
The starters used for the alkoxylation reaction may be all
compounds R.sup.1--H (IV) (the H belongs to the OH group of the
alcohol) which, according to formula (IV), have at least one
reactive hydroxyl group.
In the context of the present invention, starter compounds are
understood to mean substances which form the beginning (start) of
the polyether molecule to be prepared, which is obtained by the
addition of alkylene oxide. The starter compound used in the
process according to the invention is preferably selected from the
group of the alcohols, polyetherols or phenols or acids. The
starter compound used is preferably a mono- or polyhydric polyether
alcohol or alcohol R.sup.1--H (the H belongs to the OH group of the
alcohol).
The OH-functional starter compounds used are preferably compounds
having molar masses of 18 to 2000 g/mol, especially 100 to 2000
g/mol, and 1 to 8, preferably 1 to 4, hydroxyl groups. Examples
include but are not limited to allyl alcohol, butanol, octanol,
dodecanol, stearyl alcohol, 2-ethylhexanol, cyclohexanol, benzyl
alcohol, ethylene glycol, propylene glycol, di-, tri- and
polyethylene glycol, 1,2-propylene glycol, di- and polypropylene
glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane,
glycerol, pentaerythritol, sorbitol, or compounds which bear
hydroxyl groups and are based on natural substances.
Advantageously, low molecular weight polyetherols having 1-8
hydroxyl groups and molar masses of 100 to 2000 g/mol, which have
themselves been prepared beforehand by DMC-catalyzed alkoxylation,
are used as starter compounds.
In addition to compounds having aliphatic and cycloaliphatic OH
groups, suitable compounds are any having 1-20 phenolic OH
functions. These include, for example, phenol, alkyl- and
arylphenols, bisphenol A and novolacs.
The process according to the invention can be used, according to
the epoxide and the type of epoxide ring opening, to prepare
polyether alcohols of the formula (Va) and (Vb) and mixtures
thereof.
R.sup.1--[(CR.sup.6R.sup.2--CR.sup.5R.sup.3--O).sub.nH].sub.m (Va)
or R.sup.1--[(CR.sup.5R.sup.3--CR.sup.6R.sup.2--O).sub.nH].sub.m
R.sup.1--[(CHR.sup.2--CH(CH.sub.2OR.sup.4)--O).sub.nH].sub.m (Vb)
or R.sup.1--[(CH(CH.sub.2OR.sup.4)--CHR.sup.2--O).sub.nH].sub.m
where R.sup.1 is either a hydroxyl radical or a radical of the
organic starter compound and, in this case, is a radical having at
least one carbon atom, m is a range selected from the group
consisting of 1 to 8, 1 to 6, and 1 to 4, n is a range selected
from the group consisting of 0 to 12 000, 1 to 800, 4 to 400 and 20
to 200, and the definitions of the R.sup.2, R.sup.3, R.sup.4,
R.sup.5 and R.sup.6 radicals correspond to those of the formula
(IIIa) or (IIIb).
In particular, the process according to the invention can be used
to synthesize polyethers of the formula (Va) or (Vb) which are
notable in that they can be prepared in a controlled and
reproducible manner with regard to structure and molar mass
distribution. These polyethers are suitable as base materials for
preparing, for example, polyurethanes, and are particularly
suitable for preparing products with interface-active properties,
including, for example, but not specified exclusively, organically
modified siloxane compounds. These surfactants include--but without
being limited thereto--silicone polyether copolymers as PU foam
stabilizers, and equally emulsifiers, dispersants, defoamers,
thickeners and, for example, release agents.
The process according to the invention, in which the alkoxylation
of OH-functional compounds such as alcohols, polyols, phenols or
else polyetherols is conducted by means of DMC catalysis in the
presence of particular hydrogen-substituted silicon compounds of
the formula (I) and (II), thus differs fundamentally in every
aspect from the procedure described in U.S. Pat. No. 6,713,599 B1
and removes the hitherto unavoidable coupling of DMC catalysis and
associated formation of polyethers of low polydispersity. An
instrument is thus available which allows the advantages of DMC
technology to be utilized further and in order to enhance the
flexibility of the molar mass control, in order ultimately thus to
widen the application spectrum of DMC-based products thus prepared
to the sensitive sector of interface-active applications.
The type of alkylene oxides and glycidyl compounds used, the
composition of mixtures of these epoxide compounds and the sequence
of their addition during the DMC-catalyzed alkoxylation process
depends on the desired end use of the polyether alcohols.
The reactors used for the reaction claimed in accordance with the
invention may in principle be all suitable reactor types which
allow the reaction and any exothermicity thereof present to be
controlled.
The reaction can, in a manner known in process technology, be
effected continuously, semicontinuously or else batchwise, and can
be adjusted flexibly to the production technology equipment
present.
In addition to conventional stirred tank reactors, it is also
possible to use jet loop reactors with a gas phase and external
heat exchangers, as described, for example, in EP-A-0 419 419, or
internal heat exchanger tubes, as described in WO 01/62826. In
addition, it is possible to use gas phase-free loop reactors.
In the metered addition of the reactants, a good distribution of
the substances involved in the chemical reaction is needed, i.e. of
the alkylene oxides and/or glycidyl compounds, starter, DMC
catalyst and, if appropriate, suspension medium and of the
inventive additive.
After the alkylene oxide addition and any continued reaction to
complete the alkylene oxide conversion, the product can be worked
up. The workup required here includes in principle only the removal
of undepleted alkylene oxide and any further, volatile
constituents, typically by vacuum distillation, steam or gas
stripping or other methods of deodorization. Volatile secondary
components can be removed either batchwise or continuously. In the
process according to the invention based on DMC catalysis, in
contrast to the conventional base-catalyzed alkoxylation, it is
normally possible to dispense with a filtration.
It is possible if required to remove the DMC catalyst from the
finished polyether alcohol. For most fields of use, it can,
however, remain in the polyether alcohol. It is possible in
principle, although not preferred, to remove the DMC catalyst and
to reuse it, as described, for example, in WO 01/38421. However,
this procedure is usually too complicated for the industrial scale
preparation of polyether alcohols.
The alkylene oxide compounds or, stated in general terms, epoxide
compounds are added at a temperature range selected from the group
consisting of 60 to 250.degree. C., 90 to 160.degree. C. and 100 to
130.degree. C. The pressure at which the alkoxylation takes place
is selected from a range consisting of 0.02 bar to 100 bar and 0.05
to 20 bar absolute. By virtue of the performance of the
alkoxylation under reduced pressure, the reaction can be performed
very reliably. If appropriate, the alkoxylation can be carried out
in the presence of an inert gas (e.g. nitrogen) and also at
elevated pressure.
The process steps can be conducted at identical or different
temperatures. The mixture of starter substance, DMC catalyst and
optionally additive initially charged in the reactor at the start
of the reaction can, before commencement of the metered addition of
the alkylene oxides, be pretreated by stripping according to the
teaching of WO 98/52689 (U.S. Pat. No. 5,844,070). In this case, an
inert gas is added to the reaction mixture via the reactor feed,
and relatively volatile components are removed from the reaction
mixture by applying a reduced pressure with the aid of a vacuum
system attached to the reactor system. In this simple manner, it is
possible to remove substances which can inhibit the catalyst, for
example lower alcohols or water, from the reaction mixture. The
addition of inert gas and the simultaneous removal of the
relatively volatile components may be advantageous especially at
the startup, since the addition of the reactants or side reactions
can also allow inhibiting compounds to get into the reaction
mixture.
The DMC catalysts used may be all known DMC catalysts, preferably
those which comprise zinc and cobalt, more preferably those which
comprise zinc hexacyanocobaltate (III). Preference is given to
using the DMC catalysts described in U.S. Pat. No. 5,158,922, US
20030119663, WO 01/80994 (U.S. Pat. No. 6,835,687) or in the
abovementioned documents. The catalysts may be amorphous or
crystalline.
In the reaction mixture, the catalyst concentration is selected
from the ranges consisting of >0 to 1000 ppmw (ppm by mass),
>0 to 500 ppmw, 0.1 to 100 ppmw and 1 to 50 ppmw. This
concentration is based on the total mass of the polyether
polyols.
Preference is given to metering the catalyst into the reactor only
once. The amount of catalyst should be adjusted such that there is
a sufficient catalytic activity for the process. The catalyst can
be metered in as a solid or in the form of a catalyst suspension.
Where a suspension is used, especially the starter polyether is
suitable as the suspension medium. However, preference is given to
dispensing with a suspension.
In one embodiment of the invention, the polydispersity
M.sub.w/M.sub.n is increased from about 10% to about 40% when a
silicon compound with one or more hydrogen atoms bonded directly to
the silicon atom is used as an additive to the starter mixture
composed of OH-functional starter and DMC catalyst relative to a
starter mixture without the additive. In another embodiment of the
invention, the polydispersity M.sub.w/M.sub.n is increased from
about 20% to about 30% when a silicon compound with one or more
hydrogen atoms bonded directly to the silicon atom is used as an
additive to the starter mixture composed of OH-functional starter
and DMC catalyst relative to a starter mixture without the
additive. Depending on the reaction conditions and the additives
used, even higher increases of polydispersity may be
reached/expected, e.g. from about 40% to about 100%-200%.
The examples adduced serve only for illustration, but do not
restrict the subject-matter of the invention in any way.
EXAMPLES
The values in percentage and absolute numbers of the GPC
measurements are based on typical GPC-conditions: column
combination SDV 1000/10000 .ANG. (length 65 cm), temperature
30.degree. C., THF as mobile phase, flow rate 1 ml/min, sample
concentration 10 g/l, RI-detector, analysis against polypropylene
glycol standard.
Preparation of Polypropylene Glycol by the Process According to the
Invention with Addition of an Additive.
Example 1a
A 3 litre autoclave is initially charged with 215.7 g of
polypropylene glycol (weight-average molar mass M.sub.w=2000
g/mol), 0.03 g of zinc hexacyanocobaltate DMC catalyst and 5.9 g of
heptamethylhydrotrisiloxane with an SiH content of 4.5 eq/kg
(Rhodia), CAS [1873-88-7] under nitrogen and heated to 130.degree.
C. with stirring. The reactor is evacuated down to an internal
pressure of 30 mbar in order to remove any volatile ingredients
present by distillation. To activate the DMC catalyst, a portion of
40.0 g of propylene oxide is added. After the reaction has set in
and the internal pressure has fallen, a further 944 g of propylene
oxide are metered in continuously with cooling at 130.degree. C.
and internal reactor pressure max. 1.5 bar within 60 min. The 30
minutes of continued reaction at 130.degree. C. are followed by the
degassing stage. This removes volatile constituents such as
residual propylene oxide by distillation at 130.degree. C. under
reduced pressure. The finished polyether is cooled to below
80.degree. C. and discharged from the reactor.
The resulting long-chain polypropylene glycol has an OH number of
10.2 mg KOH/g, a viscosity (25.degree. C.) of 10 400 mPas and,
according to GPC (gel permeation chromatography), a polydispersity
M.sub.w/M.sub.n of 1.8 (against polypropylene glycol standard).
Comparative Experiment to 1A) without Addition of an Additive
(Noninventive)
Example 1b
In a further reference experiment carried out analogously to
Example 1a, in accordance with the prior art to date, no additive
is added to the polypropylene glycol/DMC catalyst mixture at the
start of the alkoxylation.
The resulting long-chain, low-viscosity polypropylene glycol has an
OH number of 9.8 mg KOH/g, a viscosity (25.degree. C.) of 7100 mPas
and, according to GPC, a polydispersity M.sub.w/M.sub.n of 1.4
(against polypropylene glycol standard).
Experiment Overview 1:
Influence of the additive addition on the polydispersity using the
example of a long-chain polypropylene glycol
Starter polyether: polypropylene glycol (M.sub.w=2000 g/mol),
catalyst: zinc hexacyanocobaltate
GPC analyses against polypropylene glycol standard
TABLE-US-00001 Starter Experiment PO Amount of Reaction OH number
GPC No. DMC cat. Additive additive temp. [mg KOH/g] Mw/Mn 1a 215.7
g Heptamethyl- 5.90 g 130.degree. C. 10.1 1.8 984 g
hydrotrisiloxane 0.03 g CAS 1873-88-7 1b* 215.7 No additive --
130.degree. C. 9.8 1.4 984 g 0.03 g *= reference experiment,
noninventive
The polydispersity using the additive in the process is compared to
the reference experiment higher by 0.4, which is corresponding to
28.6 percent.
Preparation of Mixed Ethylene Oxide/Propylene Oxide-Based
Polyethers by the Process According to the Invention with Addition
of an Additive
Example 2a
A 3 litre autoclave is initially charged with 180.0 g of
polypropylene glycol monoallyl ether (weight-average molar mass
M.sub.w=400 g/mol), 0.08 g of zinc hexacyanocobaltate DMC catalyst
and 5.25 g of heptamethylhydrotrisiloxane, CAS [1873-88-7], under
nitrogen, and heated to 130.degree. C. with stirring. The reactor
is evacuated down to an internal pressure of 30 mbar, in order to
remove any volatile ingredients present by distillation. To
activate the DMC catalyst, a portion of 36.0 g of propylene oxide
is added. After the reaction has set in and the internal pressure
has fallen, 396 g of ethylene oxide and 1269 g of propylene oxide
are metered in as a mixture continuously with cooling at
130.degree. C. and internal reactor pressure max. 1.5 bar within 90
min. The 30 minutes of continued reaction at 130.degree. C. are
followed by the degassing stage. This removes volatile fractions
such as residual propylene oxide by distillation under reduced
pressure at 130.degree. C. The finished polyether is cooled to
below 60.degree. C. and discharged from the reactor.
The resulting allyl polyether has an OH number of 13.5 mg KOH/g
and, according to GPC, a polydispersity M.sub.w/M.sub.n of 1.5
(against polypropylene glycol standard).
Example 2b
In an experiment carried out analogously to Example 2a, 4.10 g of
the additive heptamethylhydrotrisiloxane (Rhodia) with an SiH
content of 4.5 eq/kg, CAS [1873-88-7], are added to the
polypropylene glycol monoallyl ether/DMC catalyst mixture at the
start of the alkoxylation.
The resulting allyl polyether has an OH number of 13.4 mg KOH/g
and, according to GPC, a polydispersity M.sub.w/M.sub.n of 1.3
(against polypropylene glycol standard).
Example 2c
In an experiment carried out analogously to Example 2a, 5.0 g of
the additive .alpha., .omega.-di-hydropolydimethylsiloxane with an
SiH content of 2.75 eq/kg, are added to the polypropylene glycol
monoallyl ether/DMC catalyst mixture at the start of the
alkoxylation.
The resulting allyl polyether has an OH number of 13.5 mg KOH/g
and, according to GPC, a polydispersity M.sub.w/M.sub.n of 1.5
(against polypropylene glycol standard).
Example 2d
In an experiment carried out analogously to Example 2a, 6.2 g of
poly(methylhydro)poly(dimethylsiloxane) copolymer with an SiH
content of 2.5 eq/kg are added as an additive to the polypropylene
glycol monoallyl ether/DMC catalyst mixture at the start of the
alkoxylation.
The resulting allyl polyether has an OH number of 13.4 mg KOH/g
and, according to GPC, a polydispersity M.sub.w/M.sub.n of 1.5
(against polypropylene glycol standard).
Comparative Experiment to 2a-d) Without Addition of an Additive
(Noninventive)
Example 2e
In a further reference experiment carried out analogously to
Example 2a, in accordance with the prior art to date, no additive
is added to the polypropylene glycol monoallyl ether/DMC catalyst
mixture at the start of the alkoxylation.
The resulting allyl polyether has an OH number of 13.4 mg KOH/g
and, according to GPC, a low polydispersity M.sub.w/M.sub.n of 1.05
(against polypropylene glycol standard).
The experimental overview 2 shows that the polydispersity by using
the additive in experiments 2a), 2c) and 2d) is higher by 0.45
points or 42.8 percent if compared to the reference experiment 2e).
In experiment 2b) the polydisperity is higher by 0.25 points or
23.8 percent if compared to the reference experiment 2e).
Experiment Overview 2:
Influence of the additive addition on the polydispersity using the
example of an allyl polyether based on ethylene oxide and propylene
oxide.
Starter polyether: polypropylene glycol monoallyl ether
(M.sub.w=400 g/mol)
Catalyst: zinc hexacyanocobaltate
GPC analyses against polypropylene glycol standard
TABLE-US-00002 Starter Experiment EO Amount of Reaction OH number
GPC No. PO DMC cat. Additive additive temp. [mg KOH/g] Mw/Mn 2a 180
g 0.08 g Heptamethyl- 5.25 g 130.degree. C. 13.5 1.5 396 g
hydrotrisiloxane, 1305 g CAS 1873-88-7 2b 180 g 0.08 g Heptamethyl-
4.1 g 130.degree. C. 13.4 1.3 396 g hydrotrisiloxane, 1305 g CAS
1873-88-7 2c 180 g 0.08 g .alpha.,.omega.-dihydropoly- 5.0 g
130.degree. C. 13.5 1.5 396 g dimethylsiloxane 1305 g 2d 180 g 0.08
g Poly(methylhydro) 6.2 g 130.degree. C. 13.4 1.5 396 g
poly(dimethyl- 1305 g siloxane) copolymer 2e* 180 g 0.08 g -- no
additive 130.degree. C. 13.4 1.05 396 g 1305 g *reference
experiment, noninventive
Having thus described in detail various embodiments of the present
invention, it is to be understood that many apparent variations
thereof are possible without departing from the spirit or scope of
the present invention.
* * * * *